Abstract The purpose of this study was to assess the potential cytotoxicity of impression materials. The impression material brands tested included Impregum, Reprosil, Surgident, Permlastic, Jeltrate Regular and Jeltrate Fast Set. These impression materials and their components were tested for their possible cytotoxic effects by three different methods. The results showed that all impression materials were cytotoxic to some degree by all three assay methods and some of the components were also cytotoxic. These results support the literature showing in vivo adverse effects of certain impression materials and/or their components in patients and practitioners.